That centerboard is weighted and part of the ballast of the boat, so most of the time you want it locked in place. You might crank up that keel when going dead downwind, reduce the drag and gain a fraction of speed.

the danger of letting it "just hang" is that if the boat happens to heel further than expected (say you are suddenly hit by a gust), the centerboard could fold up into the trunk, immediately eliminating precious righting moment. And then, Blammo, you are capsized. (I discovered this effect so many years ago a Newport 17, a similar boat)

I'd say that you'd be better served by locking it in place and learning the shoals in your area.

 

if it is a swing keel , and winds are strong enough to heel you so as to broach the rudder, the boat will swing itself around with a force hard enough to slam the keel into the housing , possibly putting a large hole into bottom? i'm just saying, thats the idea to locking it down. hope that helps.

 

What Mac suggests about the keel moving around and causing damage is very pertinent. To add to that, if the keel is attached to the hull in two places - at the pivot point and also at the lockbolt point, and you hit something, the force of the contact is spread over the two points - as designed. If you hit something with the keel attached at only one point, all the force is concentrated on that one point --- and it will be more likely to break. Another issue is that when you hit something, it is almost never absolutely lined up fore and aft with the boat. There is almost always a sideways component involved. putting all the force of contact on the one pivot point of the swing keel, and having it be partially sideways, could be a good way to have the keel completely rip off and leave a big hole in the bottom of your boat. I would sail with the keel locked in place, and if I got stuck on a mudbank and couldn't get off any other way, THEN I'd try pulling the lockbolt to see if that would help. If I did that, however, I'd worry about bending things so that they wouldn't slide into place the way they used to. Four feet of draft is not so much that you shouldn't be able to hop out and push the boat off most sandbars. Just getting off the boat to do that might float it, too. Make sure you hold onto a line so it doesn't get away!

 

My O'Day Mariner has a 165 lb cast iron "weighted centerboard". There is no provision for locking it in the down position and it has never been a problem for me when sailing.

 

A weighted centerboard is just that. It has been designed as a centerboard, without any locking mechanism. The steel centerboard on a Lightning weighs about 150 pounds: same deal: no locking mechnanism. If the boat has been DESIGNED with a locking mechanism however, it makes sense to use it as it was designed. It may function without the keel (note the term keel, rather than centerboard) locked, but then, why IS there a lock? Probably because the builder thinks that the keel represents too big a weight to have waving around loose down there and still be safe. If he didn't think a lock was called for, he wouldn't have included it. Though there may be a (large) safety factor in the construction that enables people to "forget" locking the keel and not sink right away, I would still use it.

 

Different boat with a much heavier keel, but I've always found Catalina Direct's synopsis of how to handle the locking bolt on a Catalina 22 to be reasonable and even handed, and I think the logic still applies:

https://www.catalinadirect.com/index.cfm?fuseaction=feature.display&feature_ID=45

My boat has had the locking bolt removed by a previous owner and I've never had a problem. I appreciate it because I sail on very shallow water and I rub more often than I care to admit, although the fact that I can't lock it down is one of the things that makes me nervous about taking longer trips or going out into the ocean.

 

OK...foolish question. Do any boats use the equivalent of a shear pin for the lock? Thus preventing damage from a hard grounding?